The Eye

• Cornea

  • Refracts light into eye
  • Protective outer layer of the eye - creates barrier against dust and bacteria
  • helps focus light onto retina
• Iris

  • Sphincter muscle
  • Controls how much light let into eye
  • Contains antagonistic muscle pair of radial and circular muscles
• What do radial and circular muscles do when there is less light?

  Radial muscles contract, circular muscles relax, causing pupil to become larger (dilate) to allow more light in -> raDial muscles Dilate
• What do radial and circular muscles do when there is more light?

  Circular musles contract, radial muscles relax, causing pupil to become smaller and allow less light in
• Pupil

  • Hole in iris
  • allows light to enter into the eye
• Why does the iris appear black?

  Light only enters and very little light exits out the pupil
• Cilliary Muscle and suspensory ligaments

  • antagonistic muscle pair
• To see near objects, what do cilliary muscles and suspensory ligaments do?

  Ciliary muscles contract, suspensory ligaments loosen, lens becomes fatter, light rays refracted more strongly